package com.liuyang.demo.collection;

import java.util.*;

public class ListSetDemo {
    public static void main(String[] args) {
        LinkedList<String> a = new LinkedList<>();

        List<String> b = new ArrayList<>();

        Set<String> c = new HashSet<>();
        c.add("a");
        c.add("a");

        LinkedHashSet d = new LinkedHashSet();

        List list = Collections.synchronizedList(b);

        List emptyList = Collections.EMPTY_LIST;
        Map emptyMap = Collections.EMPTY_MAP;
        Set emptySet = Collections.EMPTY_SET;
    }

}
